Factors Associated with Duck Nest Success
in the Prairie Pothole Region of Canada

Adult Mortality

We compared species composition of ducks found dead with species composition of
ducks in the breeding population using a chi-squared goodness-of-fit test. Comparisons
were done separately for each year, 1983-85. For the 5 common species, we used
an r-sample binomial test (Bain and Engelhardt 1987) to examine the null
hypothesis that male and female ducks were killed in proportion to their abundance
in the breeding population. We assumed that breeding populations contained equal
proportions of males and females, although continental populations of these species
are thought to contain more males than females (Bellrose 1980). We first simultaneously
tested the null hypothesis for all years for each species to determine overall
significance (P = 0.05). Significant results for a species were then examined
by individual year to isolate the source of significance. For each species, we
excluded years with <10 specimens identified to sex, because distribution of the
test statistic is unknown for small samples.
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